The invention arose during continuing development efforts in improving pressure vessels such as shown in U.S. Pat. No. 4,474,215, incorporated herein by reference.
In the present invention, improvements are made in the diaphragm peripheral edge seal which provide higher compression of the rubber diaphragm material at the sealing point, yet still enable ease of assembly. This is accomplished by reducing the amount of diaphragm material requiring compression. Instead, only certain areas are compressed and are chosen to subject the sealing area to a direct force. A radial outward force compresses the peripheral edge of the diaphragm radially outwardly against a tapered wall portion of the vessel shell which compresses the outer side of the diaphragm edge downwardly into the widest radial area portion of a bulge in the shell wall to enhance the seal thereat. The radial force of the compressed area is also allowed to spread out the diaphragm material along the inner side of the diaphragm edge into less compressed areas to enable the noted reduction in the amount of diaphragm sealing material requiring compression, all while improving the seal and at the same time maintaining ease of assembly.